Can someone give me a good idea of how much fuel a pair of 535 HP 6V92TA Detroits will burn in a 34,500 lb express cruiser? I am thinking somewhere between 40 and 50 gph combined at 1900-2000 rpm cruise. Am I way off?
The propeller load curves from the DD book show under 40 gph for a pair of 550s. The measured fuel consumption from a pair of 475 hp 6V-92s in a 1987 Bertram 42 Conv, 39,600# displ. (full fuel & water, 6 people, 1200# gear) show over 60 gph. Obviously, your mileage may vary.
I've run a few boats with 6v92's and cruising at 1950rpms I've noticed the fuel burn to be around 50 gph with both engines.